Lanark, IL Weather & Growing Conditions
Tonight
53°F
Rain Showers
Rain showers. Mostly cloudy. Low around 53, with temperatures rising to around 55 overnight. South wind 10 to 15 mph, with gusts as high as 25 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 53°F | Rain Showers | 10 to 15 mph S | 87% |
| Wednesday | 58°F | Chance Rain Showers | 15 mph SW | 45% |
| Wednesday Night | 45°F | Chance Rain Showers | 15 mph SW | 27% |
| Thursday | 55°F | Chance Rain Showers | 10 to 15 mph W | 53% |
| Thursday Night | 39°F | Slight Chance Rain Showers then Mostly Cloudy | 10 mph N | 16% |
| Friday | 49°F | Partly Sunny | 5 to 15 mph N | 4% |
| Friday Night | 30°F | Mostly Clear | 0 to 5 mph N | 0% |
| Saturday | 51°F | Sunny | 0 to 5 mph NW | 0% |
| Saturday Night | 32°F | Mostly Clear | 5 mph W | 2% |
| Sunday | 56°F | Sunny | 5 to 10 mph W | 4% |
| Sunday Night | 34°F | Mostly Clear | 0 to 5 mph W | 0% |
| Monday | 61°F | Sunny | 0 to 10 mph SW | 0% |
| Monday Night | 38°F | Mostly Clear | 5 to 10 mph W | 0% |
| Tuesday | 61°F | Sunny | 5 mph NW | 0% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Lanark, IL
Last spring frost
May 2
First fall frost
Oct 7
Growing season
154 days
Hardiness zone
5a
Explore more for Lanark, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Mt Carroll, Il (8.8 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.